The invention relates to a sealing bellows for a ball joint which closes on opening in a ball joint housing through which a rotatable or pivotal ball stud extends. The sealing bellows is made from an elastomeric material and has a large diameter opening that circumscribes the joint housing and a small diameter opening sealingly engaging the ball stud. The sealing bellows has a plurality of axial hose sections continuously folded one into the other and at least partly overlapping each other. The hose sections are joined with each other by circumferential folds and have a progressively decreasing diameter beginning from the nonfolded hose section fastened to the joint housing.
U.S. Pat. No. 2,264,728 discloses a hose type sealing bellows for a universal joint or the like and having openings for attachment to the joint parts pivotal relative to each other. The sealing bellows has radially extending hose sections joined by folds extending radially inward and radially outward. The folds may be thickened.
This previously known sealing bellows has the disadvantage of having a large construction volume because of its radially extending folds. This construction volume is considerably further increased in the radial direction when the sealing bellows is deformed by an angular position of the joint parts. In this case, the thickening on the folds causes the sealing bellows to bend outwardly at the location of the thickening so as not to touch the universal joint. Therefore, the hose sections are insufficiently protected against mechanical damage. Namely, on the outer side of the universal joint points, the sealing bellows is considerably spread out, so that the hose sections are practically exposed.
German Published Application No. 1,286,823 discloses an elastomeric sealing bellows for ball joints having a form of an inverted cup having an opening for attachment to a joint housing, and another opening abutting a sealing ring circumscribing the ball stud. This previously known sealing bellows has hose sections folded one onto the other and joined together by circumferential folds. The hose section that surrounds the ball stud extends radially further outside than the other hose sections which are continuously folded thereonto. This succession of hose sections folded one onto the other results in disadvantageously large construction volume of the sealing bellows as the sealing bellows at the fold of the radially outermost hose section, has a much larger diameter than the joint housing to provide sufficient clearance for movement of the folded-in hose sections.
U.S. Pat. No. 3,650,552 discloses a ball joint with an elastomeric sealing bellows having three cylindrical hose sections of which the outermost hose section is connected by an arched outwardly fold, with a first folded-in hose section which, in turn, is connected by an arched inwardly fold, with a second folded-in hose section. This previously known sealing bellows is not protected from mechanical damage, so that, for example, when used in steering rods of motor vehicles, it can be damaged by whirling solids. Moreover, its form stability is not especially good, since its folds and hose sections can be displaced with a rotary or angular movement, and the build-up of a return force is also prevented by an early breaking of the folds. Consequently, this known sealing bellows, at its ball stud side opening, is guided on both sides in a groove so that it regains approximately its original form when the ball stud occupies its intermediate position. Finally, the space required for this sealing bellows is large since the outermost hose section is subjected to large deformations.
European Patent No. 0 157 559 discloses a sealing bellows for joint connections having a hose-form body made from a flexible material and fastened at the end openings thereof to the joint parts with at least one hose section being folded onto an adjacent hose section. This sealing bellows has essentially the same disadvantages that the sealing bellows for ball joints described above.
The object of the invention is a sealing bellows which is better protected against mechanical damage, is more form-stable, but which has sufficient softness and a large deflection range and, at the same time, even with great deflection angles of the ball stud, requires little space.